Casting sheet composite body and method for producing the same

ABSTRACT

A method for producing a cast/sheet-metal composite body, comprising the following steps: provide a casting mold ( 12 ), place at least one sheet-metal part ( 11 ) in the casting mold ( 12 ), produce a cast part ( 2 ) interconnected with the at least one sheet-metal part ( 11 ), and apply pressure to the at least one sheet-metal part ( 11 ) to form a hollow space ( 8 ).

The invention concerns a cast/sheet-metal composite body and a methodfor producing it.

BACKGROUND OF THE INVENTION

If passages for a cooling fluid are to be integrated in a housing madeof metal casting, e.g., for an alternator, two methods for producingthem are known. On the one hand, the housing can be produced using thesand-casting method with an appropriate core. This is expensive forseries production in particular. On the other hand, the housing can beproduced in two parts using the diecasting method—if the geometry allowsthis—whereby the two housing parts must then be interconnected in sealedfashion. This is expensive as well.

SUMMARY OF THE INVENTION

The invention is based on the object of creating a method for producingcast parts in which passages can be integrated as easily as possible.The essence of the invention lies in the creation of a cast/sheet-metalcomposite body, in which, after the cast part is produced, theintegrated sheet-metal part is deformed in plastic fashion. Theadvantage of this is that fluid-sealed and pressure-sealed passages canbe formed even in highly inaccessible regions of a complex cast part.

The sheet metal part is composed of two superimposed metal sheets. Theadvantage of this is that the hollow space formed is bordered only bymetal sheets and not by the cast part itself. As a result of this,greater resistance to corrosion can be attained.

Additional features and details of the invention result from thedescription of three exemplary embodiments with reference to thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first method step for producing a composite bodyaccording to an initial exemplary embodiment,

FIG. 2 shows a second method step for producing a composite bodyaccording to the first exemplary embodiment,

FIG. 3 shows a third method step for producing a composite bodyaccording to the first exemplary embodiment,

FIG. 4 shows a fourth method step for producing a composite bodyaccording to the first exemplary embodiment,

FIG. 5 shows a fifth method step for producing a composite bodyaccording to the first exemplary embodiment,

FIG. 6 shows a sixth method step for producing a composite bodyaccording to the first exemplary embodiment,

FIG. 7 shows a cross section of the composite body according to thefirst exemplary embodiment,

FIG. 8 shows a sheet-metal part for producing a composite body accordingto a second exemplary embodiment,

FIG. 9 shows a top view of the sheet-metal part according to thevisual-direction arrows IX—IX in FIG. 8,

FIG. 10 shows a further method step for producing the composite bodyaccording to a second exemplary embodiment,

FIG. 11 shows a top view according to the visual-direction arrows XI—XIin FIG. 10,

FIG. 12 shows a further method step for producing the composite bodyaccording to the second exemplary embodiment,

FIG. 13 shows a cross-sectional illustration of the composite bodyaccording to the second exemplary embodiment,

FIG. 14 shows a cross-sectional illustration of the composite bodyaccording to a third exemplary embodiment,

FIG. 15 shows a top view of the sheet-metal part of the composite bodyaccording to the third exemplary embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method for producing a cast/sheet-metal composite body 1 will bedescribed hereinbelow within the scope of a first exemplary embodimentwith reference to FIGS. 1 through 7. The first description refers to thefinished composite body 1, with reference to FIG. 7. The composite body1 comprises a cast part 2. Said cast part includes two annularconnecting bars 3 arranged side-by-side and bordering an upwardly openconnection bore 4 in each case. The connecting bars 3 are interconnectedvia a base plate 5. A sheet-metal plate 6 extending substantiallyparallel to the base plate 5 is located underneath said base plate,which said sheet-metal plate is embedded and fixed in the cast part 2along its entire edge portion 7 in pressure-sealed fashion. A passage 8is formed between the base plate 5 and the sheet-metal plate 6, whichsaid passage interconnects the two connection bores 4, inside each ofwhich a connection fitting 9 is fixed by means of press fit. A tube 10for the supply or carrying away of cooling water is secured to each ofthe connection fittings 9, which extend past the respective connectingbars 3.

To produce the composite body 1, a sheet-metal blank 11 formed as asheet-metal part is placed in a diecasting mould 12 composed of a firsthalf 13 and a second half 14, as shown in FIG. 1. The sheet-metal blank11 comprises an upwardly projecting edge portion 7. The cast part 2 isthen created in the mould 12, whereby the edge portion 7 isinterconnected with the cast part 2 in sealed fashion. The sheet-metalplate 6 lies on the underside of the base plate 5. The cast part 2 isthen machined-down and deburred, as shown in FIG. 3. After this, asshown in FIG. 4, the connection fittings 9 are inserted in the bores 4,in which they are fixed by means of press fit. The cast part 2 is thenplaced in a pressure application mould 15 that is composed of a firsthalf 16 and a second half 17. The mould 15 comprises an interior space18 that basically matches the exterior contour of the part shown in FIG.4. A recess 19 designed in the shape of a passage is provided in thehalf 17, adjacent to the exposed sheet-metal plate 6. Sealing rings 20are arranged on the bars 3 to pressure-seal the interior space 18 fromthe environment. The half 16 comprises two upwardly open connectionpassages 21, by means of which the sheet-metal plate 6 is acted uponwith pressure via compressed air or a pressurized fluid. As a result ofthe pressure application, the sheet-metal plate 6 is pressed into therecess 19 and deformed in plastic fashion until it takes on the shapeshown in FIGS. 6 and 7. As a result of the plastic compression strain,the passage 8 is produced between the base plate 5 and the sheet-metalplate 6, which said passage interconnects—in sealed fashion—theconnection fitting 9 situated on the left with the connection fitting 9situated on the right. In the step shown in FIG. 6, the composite body 1is subjected to an air-tightness test using compressed air, wherebypotential leaks are detected over time by means of a drop in pressure.

The method described above has numerous advantages. By using comparablysimple diecasting moulds 12, it is possible to produce cast/sheet-metalcomposite bodies 1 having inboard passages 8. The fact that installationspace can be spared overall is of central significance here. The moulds12 do not require cores, which would have to be removed in expensivefashion. Production costs can be greatly reduced as a result. Inparticular, single-component housings can be combined with heatexchangers, and they can be interconnected even in the case ofgeometrically complex shapes. When heat exchangers are involved, acooling fluid is conducted through the passages 8, so that the heatgiven off at the composite body 1 can be dissipated particularlyefficiently, since the thermal conduction paths to the cooling systemare shortened. Moreover, by using sheet-metal parts, the thickness ofthe passage walls can be reduced—at least on one side—in comparison witha wall consisting of cast material. Further installation space is sparedas a result.

A second exemplary embodiment of the invention is described hereinbelowwith reference to FIGS. 8 through 13. Identical parts are assigned thesame reference numerals as in the first exemplary embodiment, thedescription of which is herewith referred to. Parts that arefunctionally identical but different in terms of design are assigned thesame reference numerals plus one superscript mark. As in the firstexemplary embodiment, the finished composite body 1′ is describedinitially with reference to FIG. 13. The method for producing thecomposite body 1′ is then explained with reference to FIGS. 8 through12. The composite body 1′ is a collector-ring end shield for anelectrical alternator. It comprises an annular-cylindrical housing wall22 having a center longitudinal axis 23 and a base 24 extending at aright angle to the center longitudinal axis 23. A roller-bearing seat 25for housing a rotor shaft is arranged in the center of the base. Anaxially projecting annular frame 26—which is concentric with saidroller-bearing seat and has a larger diameter—is interconnected with thebase 24, which said annular frame radially borders a fan wheel space 27in the direction toward the center longitudinal axis 23. An annularwinding head space 28 for a winding head of the stator of the alternatoris located between the annular frame 26 and the housing wall 22.Distributed around the circumference, bores for clamping bolts areprovided on the outside of the housing wall 22 extending parallel to thecenter longitudinal axis 23 to interconnect the two end shields of thealternator. A plurality of fan recesses 30 is provided in the base 24,between the external circumference of the roller-bearing seat 25 and theannular frame 26, which said fan recesses connect the fan wheel space 27with the environment. A heat exchanger 31 is provided in the housingwall 22 and in the base 24. Said heat exchanger is composed of anannular passage section 32 that is arranged circumferentially on theinside of the wall 22, as well as a U-shaped passage section 33interconnected with the passage section 32, which said U-shaped passagesection encloses the roller-bearing seat 25 while forming a keyholeopening 34. The passage sections 32 and 33 are bordered by an internalmetal sheet 35 and an external metal sheet 36 that are superimposedalong their edges and are friction-welded to each other along one edgeportion 7′. The metal sheets 35 and 36 are positioned, inpressure-sealed fashion, in the unit—comprising wall 22 and base24—developed as cast part 2′ along the edge portion 7′, and they arefixed there. In the region of the lower end of the passage section 32,the exterior metal sheet 36 has two radially outwardly extendingconnection openings 37 that are connected via a connection passage 38arranged on the wall 22 with a connection fitting 9 extending parallelto the center longitudinal axis 23, which said connection fitting isfixed in a connection bore 4 with press fit. One of the two connectionfittings 9 serves to supply cooling water, and the other serves to carrycooling water away.

The chronological sequence of the production method of the compositebody 1′ is described hereinbelow with reference to FIGS. 8 through 12. Asheet-metal blank 11′ developed as sheet-metal part and having thestructure shown in FIGS. 8 and 9 is first produced. The sheet-metalblank 11′ has a ring portion 39 and a base portion 40, whereby the baseportion 40 basically comprises a U-shaped cross section, and the twoarms of the U are developed integral with the ring portion 39 at theirupper ends. The sheet-metal blank 11′ is composed of two superimposedmetal sheets, i.e., the interior metal sheet 35 and the exterior metalsheet 36, which are friction-welded to each other along the edgeportions 7′. The sheet-metal blank 11′ is placed in a diecasting mouldand covered with a cast part 2′ applied by injection moulding. Theresult is shown in FIGS. 10 and 11. In the next step, deburring andmachining-down takes place, and the connection fittings 9 are inserted.Following this, the cast part 2′ is placed in a pressure-applicationmould 15′ in which recesses 19′ are provided adjacent to the exposedmetal sheets 35 and 36. The space between the metal sheets 35 and 36 isthen acted upon with compressed air, so that the interconnected passagesections 32 and 33 are produced. The finished composite body 1′, shownin FIG. 13, is then subjected to an air-tightness test.

Due to the combination of diecast and sheet-metal parts, a heatexchanger 31—in the case of the composite body 1—can be positioned inthe end shield of an alternator, so that the waste heat produced can bedissipated without a problem, even in the case of increased-outputalternators. The total device is extremely space-saving. The coolantpassage 8′ composed of the passage sections 32 and 33 is bordered onlyby the metal sheets 35 and 36, but not by the cast material. Aluminum isoften used as the material for the metal sheets 35 and 36. Due to itsdegree of purity, aluminum is much more resistant to corrosion in thepresence of fluids than the alloy used for the metal cast.

A third exemplary embodiment of the invention is described hereinbelowwith reference to FIGS. 14 and 15. Identical parts are assigned the samereference numerals as in the first exemplary embodiment. Parts that arefunctionally identical but different in terms of design are assigned thesame reference numerals plus two superscript marks. The composite body1″ represents an annular-cylindrical housing wall 22″ in which a heatexchanger 31″ is integrated. The composite body 1″ has anannular-cylindrical housing wall 22″ in which a sheet-metal blank 1″ isintegrated that is interconnected with the cast part 2″ along the edgeportions 7″. A passage 8″ is produced between the cast part 2″ and thesheet-metal blank 11″ by means of the pressure application. Said passageis indicated in FIG. 14 by a dashed line. The sheet-metal blank 11″ isdeveloped as a strip meandering in shape that comprises recesses 41 opento the left and to the right in alternating fashion. Meander strips 42are interconnected over metal bands 43 in the region of the recesses 41.The meander strips 42 have an edge portion 7″ designed in the shape of abar. Space is created, by means of the recesses 41, for the axiallyextending clamping bolts housed in the bores 29.

1. A method for producing a cast/sheet-metal composite body (1; 1′; 1″),comprising the following steps: providing a casting mold (12), placingat least one sheet-metal part (11; 11′; 11″) in the casting mold (12),the at least one sheet-metal part (11; 11″) having a sheet-metal plate(6), producing a cast part (2; 2′; 2″) having a base plate (5) andinterconnected with the at least one sheet-metal part (11; 11′; 11″),and applying pressure to the at least one sheet-metal part (11; 11′;11″) to form a hollow space (8; 8″), the hollow space (8; 8″) beingproduced between the base plate (5) of the cast part (2; 2″) and thesheet-metal plate (6) of the sheet-metal part (11; 11″).
 2. The methodaccording to claim 1, wherein a deburring and/or a machining-down of thecast part (2; 2′; 2″) takes place before pressure is applied.
 3. Themethod according to claim 1, wherein the cast part (2; 2′; 2″)—beforepressure is applied—is placed in a pressure-application form (15; 15′)to shape the sheet-metal part (11; 11′; 11″).
 4. The method according toclaim 1, wherein the pressure application takes place by means of thepressure action of a gas or a fluid on the sheet-metal part (11; 11′;11″).
 5. The method according to claim 1, wherein the sheet-metal part(11″) is designed meandering in shape.
 6. A method for producing acast/sheet-metal composite body (1′), comprising the following steps:providing a cast mold (12); placing at least one sheet-metal part (11′)in the casting mold (12), wherein the sheet-metal part (11′) is composedof a first metal sheet (35) and a second metal sheet (36) superimposedon the first metal sheet (35) flat at least in parts; producing a castpart (2″) interconnected with the at least one sheet-metal part (11′);and applying pressure to the at least one sheet-metal part (11′) to forma hollow space (8′), wherein the first metal sheet (35) is at leastpartially lifted away from the second metal sheet (36) by means of thepressure application, forming a hollow space (8′).
 7. The methodaccording to claim 6, wherein a deburring and/or a machining-down of thecast part (2; 2′; 2″) takes place before pressure is applied.
 8. Themethod according to claim 6, wherein the cast part (2; 2′, 2″)—beforepressure is applied—is placed in a pressure-application form (15; 15′)to shape the sheet-metal part (11; 11′; 11″).
 9. The method according toclaim 6, wherein the pressure application takes place by means of thepressure action of a gas or a fluid on the sheet-metal part (11; 11′;11″).